POCT (Point Of Care Testing) units have been used in a field of clinical examinations as measuring units required for quick and accurate diagnoses and treatments in front of patients.
Examples of the POCT unit are a blood sugar sensor, a pregnancy diagnosis device, an ovulation test device, and a HbA1c/microalbumin creatinine measuring apparatus (for example, DCA2000 System produced by Bayer Medical Ltd.). Since the POCT units can focus on a marker material specific to a certain clinical condition to easily and quickly measure the marker material, they are very effective for screening and monitoring of a subject being tested. In addition, since the POCT units are comparatively small, they excel in portability and can be introduced at low cost. Further, since the POCT units do not require special expertise for operating them, they have the advantage that anyone can easily use them.
The POCT unit normally means a measuring unit used for clinical examinations in medical practice except for examination rooms of hospitals and examination centers. In recent years, the POCT units are widely used in home medical care practice because of their excellent portability, economical efficiency, and operability. Therefore, in recent years, the POCT unit means not only a measuring unit used for clinical examinations in medical practice except for examination rooms of hospitals and examination centers but also a measuring unit used in home medical care practice (see Patent Documents 1 and 2 for example).
At present, in the clinical examination, there are a large number of measurement items for accurate diagnosis and treatment of a disease of a patient. For example, for accurate diagnosis and treatment of diabetes, HbA1c, albumin, insulin, C-peptide, ketone body, and the like are set as materials to be detected in the clinical examination. In a case where a test sample is a body fluid, such as urine, major examples of a measuring method for measuring these materials to be detected are an optical measuring method and an electrochemical measuring method. By using any one of these measuring methods, the POCT units and conventional large-scale automatic measuring units measure the material to be detected which is contained in the test sample.
A conventional optical measuring method is a measuring method for measuring the material to be detected which is contained in the test sample based on optical changes. Therefore, in a case where the amount of the material to be detected which was contained in the test sample was extremely small, the measurement of the material to be detected was not accurately carried out in some cases. Moreover, in the case of using the conventional optical measuring method, a special component needs to be prepared which accurately measures the extremely small amount of the material to be detected which is contained in the test sample. Therefore, the measuring unit was not provided at a low price in some cases.
Here, disclosed as the optical measuring method capable of accurately measuring the material to be detected which is contained in the test sample without preparing the special component is an optical measuring method for generating aggregate containing the material to be detected in the test sample to measure the material to be detected based on a turbidity level of the test sample which is turbid due to the aggregate (see Patent Document 3 for example).
According to the optical measuring method disclosed as above, when carrying out the clinical examination, the urine as the test sample containing albumin (antigen) as the material to be detected and a mixture of an anti-albumin antibody (antibody) and polyethylene glycol that is an agglutination promoter are mixed with each other. Thus, in the urine as the test sample, the aggregate (to be specific, antigen-antibody aggregate) of the albumin as the material to be detected and the anti-albumin antibody is generated. Then, in this optical measuring method, the turbidity level of the test sample which is turbid due to the antigen-antibody aggregate is measured by a turbidimetric determination using light of a wavelength of 470 nm. Thus, the measurement (quantitation) of the albumin as the material to be detected which is contained in urine that is the test sample is carried out.
Patent Document 1: Japanese Laid-Open Patent Application Publication No. Hei. 7-248310
Patent Document 2: Japanese Laid-Open Patent Application Publication No. Hei. 3-046566
Patent Document 3: Published Japanese Translation of PCT Application No. 2002-509247